3 ms·

Is this really free? Doesn't it just lower the efficiency of the AC unit?

• detaro 9y ago
  Why would it lower AC efficiency? It doesn't use the exhaust air for anything. (Obviously you shouldn't block it)
• Cerium 9y ago
  No, the fans are quite strong and have an effect up to a couple meters away. I think it is more like a cat sleeping on the hood of a car. The waste heat needs to go somewhere, might as well put it in my clothes.
• eximius 9y ago
  They hang it near, not on top of the vent. And if the exhaust is outside the unit (balcony, etc), it would have basically no effect.